Modifying Brain Oscillations to Drive Perception

An important question in cognitive neuroscience is whether brain oscillations are causally related to cognitive activities or whether they represent epiphenomena. In this context, we will test hypotheses on the relationship between oscillations (in the theta, alpha and beta bands) and visual attentional selection and perception. We will test whether: - alpha-band oscillations over occipito-parietal areas regulate visual detection across the left and right visual fields for selecting visual information on the basis of its spatial location. - beta- and theta-band oscillations over occipito-parietal areas regulate the extraction of local versus global features within objects/scenes. This will be addressed by frequency-specific, rhythmic stimulation of human brain areas and by assessing its electrophysiological and perceptual consequences. Several innovative developments have emerged from brain mapping, such as mind reading. When an individual is asked to relax (wakeful rest), there is substantial fluctuation of brain activity. This occurs in organized patterns along specific neuronal networks--i.e. not randomly--and is thus likely to reflect the waxing and waning of distinct mental activities. In addition, spontaneous fluctuations in oscillatory patterns of activity seem to impact behaviour, because they are shown to co-vary with forthcoming task performance. Thus, momentary brain state can be inferred from brain mapping, and this can be used to predict imminent behaviour. We study to what extent specific patterns of brain activity can be induced by direct cortical stimulation (bypassing sensory input) to alter task performance. Our approach is based on findings in our laboratories that specific signatures of oscillatory activity predict forthcoming perception. We will use up-to-date techniques for direct (transcranial) brain stimulation at these specific frequencies to modify attention and perception. One component of the research is to identify the most effective experimental protocols to optimize our approach of driving attention and perception by direct oscillatory stimulation. This will involve specific parametric modifications of stimulation frequencies and stimulation regions as a function of ongoing brain rhythms. Another important component is to test models of attention and perception. Linking rhythmic neuronal stimulation to perception will advance theories on the functionality of brain oscillations and probe new ideas of how to bias brain function in desired direction (e.g for neurorehabilitation).

There is renewed interest in human EEG and MEG research in the particular role of oscillatory brain activity in specific frequency bands. In parallel, there is also a growing body of research on non-invasive, direct stimulation of the human brain via repetitive (rhythmic) TMS to isolate those frequencies with the strongest behavioural impact. There is, therefore, great potential in combining these two lines of research to foster knowledge of brain rhythms. Here, we aim to combine EEG/MEG and TMS to provide novel insights into the functionality of alpha, beta and theta rhythms in perception. MEG and anatomical MRIs will be used to define the individual generators of the to-be-investigated rhythms and their exact frequencies. Guided by these results, we will use rhythmic short-train TMS to stimulate cortical generators at their own (or at control) frequencies. Concurrent EEG recordings will allow the study of the effects of TMS stimulation on oscillatory brain activity. Psychophysical experiments will allow the investigation of the perceptual consequences of TMS stimulations. On the basis of experiments conducted in our laboratories, we hypothesize that stimulation at specific frequencies and sites will bias perception towards specific stimulus positions (via alpha-entrainment) or towards local versus global stimulus features (e.g. via beta/theta-entrainments). The series of experiments will improve our understanding of the role of brain rhythms in sensory selection for exploration and recognition of objects/scenes. It will also optimize stimulation protocols that mimic brain oscillations for probing their causal implication in brain function, and whose proof-of-principle is provided with included pilot data.

Beneficiaries will be researchers in fundamental and clinical interdisciplinary neuroscience, engineers and computer scientists. Possible applications in the private and military sectors are devices for monitoring visual (spatial) attention in pilots, flight controller, or surgeons. Possible applications in the clinical sector are protocols that enhance (or diminish) oscillatory brain activity patterns to modulate functions. We will describe how oscillations in specific cortical networks relate to attention and perception. In particular we will describe their modes of operation in different temporal frequency bands. This has broad implications for the understanding of the normal brain, the impaired brain, and more broadly for systems for encoding and communicating information. A detailed understanding of these oscillations is fundamental to commercial applications. Oscillatory EEG signatures could be used for online monitoring of distinct visual receptive or processing states as an effective strategy to detect lapses in attention or lapses in specialized processing, during which errors are imminent. This would be of interest in professions in which a high level of alertness and specialized processing is essential. One step further is the influencing of such oscillatory signatures by direct trancranial brain stimulation to modulate function. One prominent application is stimulation at frequencies mimicking slow wave activity during sleep, shown to promote the restorative aspects of sleep and overnight memory consolidation. Stimulation at frequencies mimicking perceptual relevant rhythms might likewise have an impact on patients with perceptual deficits, such as simultanagnosia, hemispatial neglect or blindsight. Thut, Gross and Schyns, the PIs on this project are regularly invited to give presentation of their research to large interdisciplinary and specialist audiences. They also publish in high impact journals that reach a wide audience (e.g. Nature, Nature Reviews Neuroscience, PNAS, Current Biology, PLoS, Trends in Cognitive Sciences) and more specialized journals (e.g. Cerebral Cortex, Psychological Science). Together with media relation officers of Glasgow University, the three PIs seek the best strategies to disseminate their results to the press. We are working closely with clinical colleagues and engage with engineers for creating new interdisciplinary ties within Glasgow University and affiliated Hospitals (such as the Glasgow Western Infirmary and the Glasgow Southern General Hospital) to disseminate our results for translation from behavioural studies into practice. Our research has an impact on training locally in our existing Masters and Postgraduate courses, and nationally and internationally in workshops and summer/autumn schools, where we regularly present our most recent findings among new generations of neuroscientists We also seek to engage with the wider public by various means. Glasgow University is regularly partner of the Brain Awareness Week by the Dana Foundation, and members of the Department are presenting their results at this occasion on a regular basis. The department has also strong links to the Glasgow Science Centre and to the British Association for the Advancement of Science (BAAS), where we are regularly represented at the 'Annual Science Festival'. We make use of these established links, and will seek further advice and help for a wider disseminating of our research from the press office of Glasgow University and the User Engagement Officer of our Department. This officer advises staff about specific links the Department already has with industry and the media, in addition to constantly seeking out new ways to promote engagement. Taken together, specialized and interdisciplinary talks, publication in broad readership and more specialized journals and dissemination of results to the press and colleagues guarantee a wide exposure of the results to a diverse audience.